Heat exchanger, in particular an intercooler, comprising a reinforced pipe base

ABSTRACT

A heat exchanger is disclosed, comprising a block having pipes and ribs and at least one pipe base provided with receiving openings, wherein the pipes have pipe ends, which can be held in the receiving openings and form pipe/base connections with the pipe base, the connections being at least partially reinforced by an additional sheet metal part located on the side of the pipe base facing the block, wherein the sheet metal part has insertion openings for the pipe ends.

BACKGROUND OF THE INVENTION

The invention relates to a heat exchanger according to the preamble ofClaim 1.

A weakness in known heat exchangers is the pipe/base connection(s),which are preferably formed as soldered joints between the pipe ends ofthe pipes and through-holes of the pipe base. The stress on thepipe/base joint is complex: for example, shear and bending forces arisewhich are transferred from the pipe to the pipe base. In particular, thecorner pipes, that is, the outer-positioned pipes, are subjected to anelevated stress, so that cracks can occur in the pipe ends, in the pipebase, or in the solder sites (solder meniscus) in these pipe/basejoints. In the case of heat exchangers designed as intercoolers, thepipes and the collection boxes are stressed by the interior pressure ofthe compressed charge air; likewise shear and bending stresses appear inthe pipe/base joints due to varying thermal expansion of the pipes.

Proposals are already known for reducing or eliminating these elevatedstresses: Document DE 103 16 756 A1 by the applicant discloses anintercooler with a pipe base and through-holes into which flat pipes aresoldered. Between the longitudinal sides of the pipe base and the narrowsides of the through-holes, sectioned strips are installed and aresoldered to the pipe base and to the through-holes, so that areinforcement of the pipe base and a reduction in stress peaks areachieved. This means can be applied in particular to the bending stressoccurring in this region.

Document DE 103 54 382 by the applicant discloses an intercooler withflat pipes, whose pipe ends are soldered into through-holes of the pipebase. To reinforce the pipe/base joints, an integrated component is setonto the pipe base in the region of the corner pipes, said componentextends by prong-like fingers on the narrow sides of the flat pipe intothe pipe ends, and said component is soldered to the pipe ends. Thus astress relief of the pipe/base joint is obtained, in particular in theregion of the stress peaks which occur primarily on the narrow sides.

BRIEF SUMMARY OF THE INVENTION

The purpose of the present invention is to stress relieve the pipe baseand the pipe/base joints of heat exchangers of the kind specified abovein a simple and low-cost manner, in order to ensure the leak tightnessof the pipe/base joint, even under stronger stresses.

This problem is solved by the features of claim 1. According to theinvention, a sheet metal part with insertion openings for the pipe endsis provided that is located on the outside of the pipe base that is, onthe side facing the block. The sheet metal part surrounds thecircumference of the pipe by its insertion openings and is positivelyconnected thereto. On the other side, the sheet metal part lies upon theunderside of the pipe base and is positively connected to the pipe basein this region, preferably by soldering. This yields—at least in partfor the highly stressed pipe/base connections—a force transfer platewhich evens out and reduces the forces transferred from the pipe intothe pipe base. Preferably, the invented force transfer plate is used forthe corner pipe, that is, for the outer pipe of the block, since thatpipe is exposed to the greatest stress. It is an advantage herein thatthe invented sheet metal part is easy to manufacture from a plate strip,can be connected in part with the same tools used for the openings, andis easy to connect to the pipe base and the pipes during the solderingprocess. Thus, the critical pipe/base joints are sufficiently stressrelieved.

In one favorable embodiment of the invention, the pipes are designed asflat pipes and the receiving openings of the pipe base as through-holes.The openings for insertion of the pipe ends into the force transferplate are likewise designed as through-holes. Favorable solderingconditions are thus obtained both on the base side and on the side ofthe force transfer plate, since the through-holes of the base and thethrough-holes of the force transfer plate are oriented in oppositedirections. This ensures the advantage of a stable seat for the pipe inthe base, in particular with regard to bending and shear stresses.

According to one additional, preferred embodiment, the pipe base is partof an open box section, like that used, for example, for so-calledall-metal or all-aluminum heat exchangers. The additional sheet metalpart is designed as a reinforcing or supporting plate such that itencompasses at least a portion of the pipe base, preferably in theregion of a separating wall, and also encompasses parts of the twolongitudinal sides of the box section, that is, is matched to the boxsection. The pipe base is slightly domed toward the block side and hasinwardly directed through-holes, between said holes there are convexregions curved outward that in a longitudinal cross section through thebox section have a crest, and in the transverse cross section have acrest line through the crest. According to one preferred embodiment ofthe reinforcing plate, said plate rests upon the crest lines and forms acontact zone which is preferably used as solder zone. Thus, a solid,positive connection is created between the reinforcing plate and thepipe base, which results in a significant reinforcement, in particularin the event of interior pressure acting on the box section. Thereinforcing plate is cut out in the region of the through-holes and ofthe flat pipe extending into the through-holes, and thus has a pluralityof binding bands located between the pipes or through-holes, said stripslie against the crest lines and thus reinforce the pipe base. Due to thereinforcement and stiffening of the pipe base, the pipe base joints areat the same time stress relieved, so that an improved leak tightness andan increased life of the heat exchanger is achieved.

The invented force application or reinforcing plate can be used inparticular on intercoolers in which hot, compressed charge air for aninternal combustion engine, in particular for motor vehicles, is cooled.In intercoolers the stresses caused by the varying thermal expansions ofthe pipes are particularly critical, that is, the invented forceapplication or load transfer plate has a particularly favorableadvantage for intercoolers, since they are subject to an increasedinterior pressure due to the compressed charge air.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One embodiment of the invention is illustrated in the figures and willbe explained in greater detail below. We have:

FIG. 1 a section of an intercooler with the invented load transfer plate

FIG. 2 the load transfer plate shown as a single part

FIG. 3 a box section with reinforced pipe base

FIG. 4 a longitudinal cross section through the box section and

FIG. 5 a transverse cross section through the box section

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a corner section of an intercooler 1 which has a block 4consisting of flat pipes 2 and corrugated ribs 3. This block is sealedoff by a side plate 5 at the outermost corrugated rib 3. A pipe base 6is connected to the block 4; said pipe base has through-holes 7 to holdthe flat pipe ends 2 a. To illustrate the pipe/base connection betweenflat pipe end 2 a and through-hole 7, the pipe base 6 is cut open toshow the through-hole 7, a flat pipe 2 and the side plate 5. The pipeends 2 a are soldered to the upward directed (in the figure) forthrough-holes 7 and form the pipe/base connection. Furthermore, thecorrugated ribs 3 are soldered to the flat sides of the flat pipe 2,likewise the side plate 5 is soldered to the corrugated rib 3 and thebase 6, which has a strip 6 a that is surrounded by a claw 5 a of theside plate 5. A cover or collector box (not illustrated) sits upon thepipe base 6 and is preferably soldered to the edge region of the pipebase 6. Alternatively, however, a plastic box could be used which can bejoined to the pipe base 6 by a suitable mechanical clamping connection.To this extent the intercooler 1 corresponds to the prior art.

According to the invention a reinforcing plate part 8, a so-called load-or force-transfer plate, is located on the underside or outside of thebase 6 (the side facing the ribs 3). Said plate is connected to the pipebase 6 by soldering. The reinforcing plate 8 has downward pointing (inthe drawing) through-holes 9 in the region of the pipe 2, said holessurround the pipe 2 and are soldered to the pipe ends 2 a. Thus the pipeend 2 a is inserted into two oppositely oriented through-holes 7, 9 ofthe pipe base 6 and of the reinforcing plate 8. In the figure it isevident that due to the opposing orientation of the through-holes, agreater fixing length X for the pipe is obtained, so that the forces andmoments transferred from the pipe 2 to the base 6 are on the one handintroduced into the reinforcing plate 8, and on the other hand areintroduced directly into the pipe base 6 via the through-holes 7.Elevated stresses and stress peaks are thus diminished. The loadtransfer plate 8 is preferably provided for the outermost three pipes 2,the so-called corner pipes, because the greatest stress appears there.In another embodiment, in particular for an intercooler, which isexposed to different, in particular more powerful stresses, thereinforcing principle is applied in larger regions, in particular, forexample, across the entire length of the block if so required. Otherwisethe load transfer plate 8 extends across the entire width of the pipebase 6 and is matched to the contour thereof, so that a full-surfacesoldering and thus a well-distributed force transfer will occur.

FIG. 2 shows the load transfer plate 8 as a detailed part with threethrough-holes 9, which are located here (in the figure) on the top side8 a and which are formed from the plate 8. The through-holes 9 areproduced in a known manner by hole punching. Between the through-holes 9there are flat bands 10 adapted to the base contour, whereas the outeredges 11, 12 running transverse thereto, are slightlycurved—corresponding to the contour of the pipe base 6—in order toentirely surround the rounded area of the pipe base 6. As is evidentfrom the figure, the through-holes 9 each have an inner, circumferentialflange 9 a which rests against the outer perimeter of the flat pipe ends2 a and allows a circumferential, large-area soldering. By means ofthese soldered areas, the forces and moments initially in the pipe aretransferred to the reinforcing plate 8 and then to the pipe base 6.

The assembly of the load transfer plate 8 is quite simple: aftercompletion of the block 4 (cassetting of pipes 2 with ribs 3), the loadtransfer plate 8 is set onto the pipe ends 2 a, preferably at the cornerpipe, and specifically in such a manner that the through-holes 9 aredirected toward the corrugated ribs 3. Next, the pipe base 6 is put inplace, so that the protruding pipe ends 2 a are inserted through thethrough-holes 7 of the pipe base 6. Next, the pre-assembled unit—perhapswith a solderable collector box—is placed into a soldering furnace (notillustrated) and soldered there, so that a soldered joint is formedbetween the through-holes 7 and 9 and pipe ends 2 a, and between theforce transfer plate 8 and pipe base 6.

FIG. 3 shows an additional embodiment of the invention for an all-metalor all-aluminum heat exchanger, of which only one open box section 20 isillustrated, which has two longitudinal sides 21, 22 and one slightlycurved pipe base 23 with inward directed through-holes 24. The boxsection 20 is sealed by a cover (not illustrated) and is used as acollector or distributor box for the heat exchanger, the flat pipes (notillustrated) of which are held by the through-holes 24. A heat exchangerof this kind, with an all-aluminum design, is fully soldered and usedprimarily as an intercooler for motor vehicles. The open box section 20is divided in the longitudinal direction by a separator wall 25 which isinstalled in the section and is soldered to it. The pipe base 23according to the invention is covered by a reinforcing plate 26 matchedto the box section 20; said reinforcing plate has lateral tabs 26 a, 26b which rest against the longitudinal side 21. In the region of thethrough-holes 24, the reinforcing plate 26, also called the supportplate, has recesses 28 and a plurality of binding bands 26 c arrangedmutually parallel to each other, said strips each being located betweenthe through-holes 24 and contacting and supporting the pipe base 23 atthat location. The corresponding contact surfaces, which are not visiblein FIG. 3, will be described in greater detail below.

FIG. 4 shows a longitudinal cross section through the box section 20according to FIG. 3 in the region of the pipe base 23, which has convexregions 27 arched outward between the through-holes 24, with theseregions having a crest 27 a. The through-holes 24 are evidently directedinward. Viewed in longitudinal cross section, the binding bands 26 c ofthe reinforcing plate 26 have a straight transverse cross section andcontact the convex regions 27 in the region of the crest 27 a or—whenviewed in cross section—along a crest line which runs through the crest27 a perpendicular to the plane of the figure. A contact surface is thusobtained which extends across the entire width of the pipe base 23, thatis, from the longitudinal side 21 to longitudinal side 22, so that thepipe base 23 can be braced against the support plate 26 and/or againstthe binding bands 26 c. The reinforcing plate 26 is soldered to the pipebase 23 and to the side walls 21, 22, and very good soldering conditionsare obtained between the convex regions 27 and the flat regions of thebinding bands 26 c, so that a corresponding solder meniscus can form.

FIG. 5 shows the box section 20 in cross section, and the inwardpointing through-holes 24 are clearly seen. Underneath the through-holesthere are convex regions 27 appearing as curved strips, and specificallywith the crest line 27 a′. Bearing directly against the crest line 27 athere are binding bands 26 c of the reinforcing plate 26, which areunder tensile stress when the pipe base 23 is deformed, and said bandsare braced laterally against the longitudinal sides 21, 22 by means ofthe tabs 26 a, 26 d.

1. A heat exchanger comprising an additional sheet metal part and ablock having pipes, ribs, and at least one pipe base having a sidefacing the block, the at least one pipe base provided with receivingopenings, wherein the pipes have pipe ends which can be held in thereceiving openings and with the pipe base form pipe/base connectionsthat are reinforced at least in part by the additional sheet metal part,wherein the sheet metal part has insertion openings for the pipe endsand is located on the side of the pipe base facing the block.
 2. Theheat exchanger according to claim 1, wherein the sheet metal part has apositive connection to the pipe ends and the pipe base.
 3. The heatexchanger according to claim 1, wherein the sheet metal part is matchedto the contour of the pipe base.
 4. The heat exchanger according toclaim 1, wherein the pipes are flat pipes.
 5. The heat exchangeraccording to claim 1, wherein the receiving openings of the pipe baseare through-holes.
 6. The heat exchanger according to claim 5, whereinthe through-holes are formed directed away from the block.
 7. The heatexchanger according to claim 1, wherein the through-openings of thesheet metal part are through-holes.
 8. The heat exchanger according toclaim 7, wherein the through-holes of the sheet metal part are formeddirected toward the block.
 9. The heat exchanger according to claim 1,wherein the sheet metal part is located in the region of an outer pipe.10. The heat exchanger according to claim 1, wherein the sheet metalpart and the pipe base each have a wall thickness, and the wallthickness of the sheet metal part is less than or equal to the wallthickness of the pipe base.
 11. The heat exchanger according to claim 1,wherein the pipe base is part of an open box section having longitudinalsides and the additional sheet metal part encompasses at least a portionof the pipe base and adjoining regions of the longitudinal sides. 12.The heat exchanger according to claim 11, wherein the pipe base is domedtoward the block side, and has regions between the through-holes thathave a convex shape in the longitudinal cross section of the box sectionand a crest and a crest line, respectively, and the additional sheetmetal part forms a contact zone with the pipe base in the region of thecrest and of the crest line, respectively.
 13. The heat exchangeraccording to claim 12, wherein the sheet metal part has binding bands inthe region of the crest lines.
 14. The heat exchanger according to claim12, wherein the additional sheet metal part is positively connected tothe pipe base in the region of the contact zone.
 15. The heat exchangeraccording to claim 11, wherein arranged in the open box section are aseparating wall, and at least in the region of the separating wall, theadditional sheet metal part.
 16. The heat exchanger according to claim1, wherein said heat exchanger is an intercooler, wherein the pipes areexposed to flowing charge air of an internal combustion engine.
 17. Theheat exchanger of claim 2, wherein the sheet metal part is soldered tothe pipe ends and the pipe base.
 18. The heat exchanger according toclaim 17, wherein the sheet metal part is matched to the contour of thepipe base.
 19. The heat exchanger according to claim 17, wherein thesheet metal part and the pipe base each have a wall thickness, and thewall thickness of the sheet metal part is less than or equal to the wallthickness of the pipe base.